This invention relates to such essentially hollow devices as endotracheal tubes, bronchoscopes, vascular and cervical dilators and the like that are adapted for removable insertion into a body opening. Although reference is made hereinafter to the term "tube", the same is intended to include essentially hollow members that may be of circular cross sectional configuration or of any other cross sectional configuration.
For more convenient explanation and understanding, reference will hereafter be made to endotracheal tubes as illustrative of the prresent invention. An endotracheal tube is used in anesthesiology by inserting the same into the patient orotracheally or nasotracheally below the glottic wall or into the trachea via a tracheostomy opening. At present, a cuff on the exterior of the tube surface is caused to expand into engagement with the trachea below the glottic wall. The cuff is usually formed as a separate sleeve on the tube exterior and is operated by the anesthetist to afford air-tight engagement with the vocal chords to affect an air-tight passage through which the anesthesiologist maintains full and essential control over the patient's ventilation. No leak between the tube and trachea should be tolerated. Hence, the air-tight connection is essential during endotracheal anesthesia.
Prior to the present invention, the endotracheal tube, being elongated, was fixed in internal and external size or cross section along the plane taken substantially perpendicular to the tube length. The tube outer diameter selected by the anesthesiologist most nearly approximated a dimension slightly inferior to or smaller than that of the patient's glottic airway. Thus, tube interior and exterior size was usually fixed. To compensate for the differences between the glottic airway and the tube selected by the anesthesiologist, the cuff on the tube exterior and distal end was inflated in the hope and expectation that it would substitute for the inaccuracy of fit between the endotracheal tube and the larger glottic airway.
Although such cuffs sometimes do close off the space between the tube and the glottic airway, they are an added obstruction to the smooth insertion of the tube into the trachea and constitute an obstruction on an otherwise smooth tube exterior that tends to lacerate the tender tissues during insertion and removal of the tube. Such prior known cuffs have also been known to leak, to rupture when expanded and even to slide or slip off the tube while still in the patient. All of these defects and problems may cause severe and sometimes fatal injury or even require repetition of the intubation procedure or the application of dangerous drugs to the patient.